where is my heater/ac control modular?
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RWD 19xx-1984 DeVille and Fleetwood,
1985-1996 Fleetwood and Brougham Forum Discussion, where is my heater/ac control modular? in Past Cadillac Vehicle Discussion; I have a 96 Fleetwood brougham that I am having a heater problem with. I have a friend that has ...
  1. #1
    terrible45 is offline Cadillac Owners Member
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    where is my heater/ac control modular?

    I have a 96 Fleetwood brougham that I am having a heater problem with. I have a friend that has a 95 and had the same problem and he told me he had to replace the Heater/AC control modular and it fixed the problem. My problem is I need to know where it is located. Is it under the dash on the passenger side of the car with all the other components and if so where? I have seen pictures of what it looks like and cant seem to locate it anywhere.

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    CadillacPimpinNOLA is online now Cadillac Owners Connoisseur
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    Re: where is my heater/ac control modular?

    before doing that, what problems you having it may be something else simple

  4. #3
    terrible45 is offline Cadillac Owners Member
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    Re: where is my heater/ac control modular?

    The heater is not blowing hot air or coming through the dash vents After making the mistake of taking it to the local dealership they changed the thermostat and heater core and after that $600 dollar bill it still isn't working. Like I posted I have a friend who's father had a 95 that did the same thing and that is the part he ended up changing to get it to work. I am open to any suggestions or help that anyone might be able to provide.

  5. #4
    j2rossit is offline Cadillac Owners Enthusiast
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    Re: where is my heater/ac control modular?

    Wow, they replaced the thermostat? and the heater core without testing it?

  6. #5
    terrible45 is offline Cadillac Owners Member
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    Re: where is my heater/ac control modular?

    Yep. I asked the same question and I asked to see the old parts and was given some lame excuse that they dispose of the parts at the end of the day. Not to mention that they never did figure out why the air was not coming through the vents

  7. #6
    CadillacPimpinNOLA is online now Cadillac Owners Connoisseur
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    Re: where is my heater/ac control modular?

    this is a pic someone made for something else but list all the components

    its prolly #4 for the heater/ac control modular , but pull the passenger side panel under the dash and make sure all the vacumm lines are plugged in and not split anywhere. seems a blend door may not be opening and allowing the air to come through.


  8. #7
    terrible45 is offline Cadillac Owners Member
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    Re: where is my heater/ac control modular?

    Checked #4 and if you turn the heat all the way up then all the way down you can see the aluminum gear turning. And the red line going in to #2 if you unplug that the air comes through the dash vents but when it is plugged in they don't work. also, the hoses going to the heater core are different in temperature. The lower one gets hot and the upper one is cold. Like I stated earlier the dealership replace the thermostat and heater core. Could this have something to do with no heat also?

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    j2rossit is offline Cadillac Owners Enthusiast
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    Re: where is my heater/ac control modular?

    Sounds to me like the heater core valve isn't opening. The question is, is it getting the signal to open or not. This should have been checked before ripping apart the car to replace the core.

    ----------

    I should mention that I don't know enough about the last gen fleetwood to state for sure that it has a heater core valve.

  10. #9
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    jayoldschool is offline GM RWD V8 addict
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    Re: where is my heater/ac control modular?

    There is no heater core valve in the LT1 cars.

    the hoses going to the heater core are different in temperature. The lower one gets hot and the upper one is cold. Like I stated earlier the dealership replace the thermostat and heater core.
    There are two possibilities. Both involve gross incompetence by the dealer. First (unlikely), is that the coolant is low or needs to be bled (air in the system). Second (probable) is that they never replaced the heater core, and your original heater core simply needs to be flushed.

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    terrible45 is offline Cadillac Owners Member
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    Re: where is my heater/ac control modular?

    Yes the coolant level is fine. After seeing the pictures I removed the panel and was able to see the heater core and it does look new. I disconnected the lines and ran water through the core and it came right through without any problem. What would I need to do to bleed the line?

  12. #11
    CadillacPimpinNOLA is online now Cadillac Owners Connoisseur
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    Re: where is my heater/ac control modular?

    air gets in the coolant system and its a pain in the ass to get out...just takes some time...the hoses them selves get plugged too. what i do is remove the 2 hoses for the heater core where the attach to the water pump and flush from there...you can squeeze those hoses and feel the crunchy build up

    but like jay said, maybe low coolant...jack the car up on the passenger side and fill the overflow bottle to the rim. see if any air burps out.

  13. #12
    terrible45 is offline Cadillac Owners Member
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    Re: where is my heater/ac control modular?

    Ok, flushed EVERYTHING radiator, heater core went as far as taking all the hoses of checking and cleaning them also. When the car is sitting in park it will get hot on auto but seems to get warmer if it is on ECON. But as soon as you take the car out and drive it, the air will turn cold within 2 to 3 blocks of where I start out from. Bled the system also and like I stated earlier the local dealership replaced the thermostat and heater core which I also inspected and found that they are both new parts. Any suggestions as to what it could be now? Is it possible it is something electronic?

  14. #13
    jayoldschool's Avatar
    jayoldschool is offline GM RWD V8 addict
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    Re: where is my heater/ac control modular?

    When the car is sitting in park it will get hot on auto but seems to get warmer if it is on ECON. But as soon as you take the car out and drive it, the air will turn cold within 2 to 3 blocks of where I start out from.
    I suspect a partially stuck open thermostat. I have had your EXACT symptoms, and this was the cause. The stat would not close all the way, leaving a small gap between the two parts that close off. I suggest buying the proper LT1 180F thermostat. Note that the LT1 uses a different stat than the old small block. If they put in an old stat, without the special O ring that goes on the edge of the stat, you'll know immediately that they screwed up, and the lack of seal around the body of the stat is causing the issue.

    This will explain everything.


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